This season, which has nearly passed us by, is the season of rich food, cool breezes, and the joys of autumn sake: hiyaoroshi.
In the simplest explanation, this sake was pressed in the spring, tanked and pasteurized once, then bottled and shipped in autumn without the second pasteurization. In technical terms, this makes it namazume.

The name has two parts: hiya means cool, and oroshi means to take down, lower, or wholesale.
I have heard several explanations for the name. One is that the sake is left hot in the tank after pasteurization in the spring, then when it cools down (hiya) it is drawn down from the tanks into bottles (oroshi). Another explanation was that when autumn comes with its cool weather (hiya) it’s safe to sell (oroshi) the namazume bottles without worry about spoiling. Other there’s are causing on those two, or almost connected to the autumn harvest. As with many old traditions, the truth is lost to time. And that’s fine.
Another name you see this time of year is akiagari, which is an interesting counterpoint to hiyaoroshi. Again, there are two parts to the name: aki is autumn, and agari is rise, or improve. The explanation for this name is that she left to mature over the summer will improve as the roughness of freshly pressed she makes and smoothes out. In other words, agari (rise) is basically the opposite of oroshi (to bring down).

The technical definition for akiagari is sake that is pressed and pasteurized in spring, then bottled and pasteurized again before shipping in fall. Now, to me, this just sounds like normal practice–two rounds of pasteurization on a sake aged for a few months. This might explain why many brewers simply ignore that definition and use the name interchangeably with hiyaoroshi, as a way to emphasize that their sake has improved from ageing during the warm summer months.
Whatever the name, these autumn sakes bring a sense of the season, with color and flavor just right for the cool weather and falling leaves. They tend to be deep, more umami laden than fresh spring sake, and are almost always great drunk warmed up. They excited I’ve of my favorite parts of enjoying sake in Japan: the seasonality of it. Shinshu nama or risshun shiboritate in spring, refreshing natsuzake in summer, hiyaoroshi in fall, steaming hot shiboritate and the first sip of the new year in winter.
So, enjoy some hiyaoroshi in the fall. Warren it up and sip as you think on the closing of the year, and sister a thought for the brewers waiting so hard, even now, to guide the rice on its way to your cup.
Kanpai.